Adhesive composition

ABSTRACT

THIS INVENTION RELATES TO AN ADHESIVE COMPOSITION WHICH CONTAINS AT LEAST ONE BISPHENOL-A/EPICHLOROHYDRIN RESIN, A POLYGLYCOL DIEPOXIDE RESIN, DICYANDIAMIDE, GLYCIDOXYPROPYLTRIMETHOXYSILANE, AND FINELY DIVIDED SILICA. THE SUBJECT ADHESIVE IS USEFUL IN BONDING STAINLESS STEEL TO GLASS.

r: 3,635,875 Patented Jan. 18, 1972 United States Patent syringe barrel with an adhesive. The adhesive of this in- 3,635,375 vention is readily adapted to securing stainless steel to ADHESIVE COMPOSITION Thomas D. Reifller, Pleasant Lake, Mich. and Ralph E. glass. Likewise, thrs adhesive will withstand temperatures Trease, Toledo, Ohio, assignors to Owens-Illinois, Inc. 5 m 5.2 200 for eXtFniied i q of N0 Drawing. Filed Dec. 26, 1967, Ser. No. 693,104 primary obgectof this invention 1s adhesive com- Im. CL (308k 1/08 position which can withstand temperatures in excess of US. Cl. 260--37 EP 8 Claims Another object of this invention is an adhesive which is particularly adapted to securing stainless steel to glass. ABSTRACT OF THE DISCLOSURE 10 Still another object of this invention are composite glass This invention relates to an adhesive composition which f {natal articles which are Secured With the adhesive 0f contains at least one bisphenol-A/epichlorohydrin resin, thls lnventloh: a polyglycol diepoxide resin, dicyandiamide, glycidoxy- Another 18 a hypodfifmlc Syringe wherein a Stainless steel needle is secured in a glass syringe barrel with the adhesive of this invention.

Finally, the objects of this invention include all the other novel features which will be obvious from the THE INVENTION specification and claims at hand.

The adhesive composition of this invention incorporates propyltrimethoxysilane, and finely divided silica. The subject adhesive is useful in bonding stainless steel to glass.

This invention relates to an adhesive composition which 20 contains at least one bisphenol-A/epichlorohydrin resin, resmous comPonents as SPec1fied m Formulae a polyglycol diepoxide resin dicyandiamide glycidoxy The adhes1ve composition of this invention can incorpropyltrimethoxysilane, and finely divided silica. The sub- P0rate from about 45 to about 70 P y Weight of all ject adhesive is useful in bonding stainless steel to glass. epoxy resin of the bisphenol-A/epichlorohydrin type, as

The invention at hand is particularly concerned with an represented in Formula I:

Formula. I

C Ha

adhesive that is useful for securing stainless steel needles to glass syringe barrels. wherein n is about .5.

The adhesive 0f the inventiflll could generally be In addition to the above specified ranges for the comib d as 3-11 epoxy b e adhesive, E ox base adhesives position of Formula I, the adhesive composition of this are known In the However these Prior art adheslves invention can contain from about 5 to about 15 percent are disadvantageous in that they tend to degrade and hence lose their adhesive properties when exposed to temperatures in excess of 200 F. This problem is evident where the articles in question must be sterilized by exby weight of an epoxy resin of the bisphenol-A/epichlorohydrin type as represented in Formula II:

posure to temperatures in excess of 200 F. The problem wherein n is about I as discussed above is particularly acute with hypodermic 0 The sub ect adhesrve composrtlon likewise contains syringes wherein the hypodermic needle is secured to thefrom about 5 to about 30 percent by weight of an epoxy resin of the polyglycol diepoxide type as represented in Formula III:

wherein n has a value of from about 3 to about 5.6.

In addition to the above-specified epoxy resin components, the subject adhesive composition contains from about 6 to about 8 percent by weight of dicyandiamide as represented in Formula IV:

Formula IV The subject composition likewise contains from about 0.6 to about percent by weight of glycidoxypropyltrimethoxysilane as represented in Formula V:

This component generally is thought to function as a coupling agent. This coupling eflect generally results in a superior bond between the epoxy resin components and glass surfaces.

Finally, for purposes of adjusting the viscosity, the adhesive of this invention can contain from about 2 to about 8 percent by weight of finely divided silica powder.

In summary, the above specified adhesive composition is represented in Table I:

TABLE I (1) An epoxy resin of the bisphenol-A/epichlorohydrin type as represented by Formula I from about 45 to about 70 percent.

(2) An epoxy resin of the bisphenol-A/epichlorohydrin type as represented by Formula II from about 5 to about percent.

(3) An epoxy resin of the polyglycol diepoxide type, as represented by Formula III from about 5 to about 30 percent.

(4) Dicyandiamide from about 6 to about 8 percent.

(5) Glycidoxypropyltrimethoxysilane from about 0.6 to about 5 percent.

(6) Silica from about 2 to about 8 percent.

A preferred composition for minimum stress in accordance with this invention is as represented in Table II:

TABLE II (1) 47.5% of an epoxy resin of the bisphenol-A/epichlorohydrin type as represented by Formula I.

(2) 12.9% of an epoxy resin of the bisphenol-A/epichlorohydrin type as represented by Formula II.

(3) 25.7% of an epoxy resin of the polyglycol diepoxide type as represented by Formula III.

(4) 6.9% of a dicyandiamide.

(5) 3.5% of a glycidoxypropyltrimethoxysilane.

(6) 3.5% of a silica.

A preferred composition for maximum resistance to autoclaving and tolerable stress for stainless steel needles to glass syringe barrels is as represented in Table III.

TABLE III (1) 63.6% of an epoxy resin of the bisphenol-A/epichlorohydrin type as represented by Formula I.

(2) 12.7% of an epoxy resin of the bisphenol-A/epichlorohydrin type as represented by Formula II.

(3) 8.5% of an epoxy resin of the polyglycol diepoxide type as represented by Formula III.

(4) 7.6% of a dicyandiamide.

(5) .8% of a glycidoxypropyltrimethoxysilane.

(6) 6.8% of a silica.

The above-specified adhesive composition is particuhesive which is capable of providing a very high bond strength. The adhesive is well-suited for use in conjunction with glass as it is clear and it is flexible enough to take up the differential stress in glass with the result that breakage does not occur when the glass article is heated up to sterilizing temperatures. When this adhesive is used, strength is retained under both wet and dry sterilization conditions.

Upon application, the adhesive composition of this invention is cured by the application of heat. Curing can be effected by heating to from about 350 to about 500 F. A more preferred range of temperatures for the curing sequence is from about 375 to about 450 F. A most preferred curing sequence is 3 /2 minutes at 425 F.

It is understood by one skilled in the art that the exact curing sequence used is dependent on many variables such as the adhesive formulation, the quantity of adhesive used, the degree of cure desired, the mass of objects being joined, etc.

The subject adhesives can be prepared by any convenient method. However, it is preferred that the components be blended together and then milled to achieve homogeniety.

It is within the purview of this invention to add to the compositions of this invention compatible materials which do not affect the basic and novel characteristics of the composition of this invention. Among such materials are coloring agents, including dyes and pigments, fillers and similar additives. Additives such as antioxidants, antistatic agents, stabilizers and anti-foaming agents, may also be added. The upper limit of the quantity of additives is usually about 20 weight percent of the product.

The adhesives as described above can be used to secure composite objects where a strong, heat-resistant, water-resistant, clear, flexible bond is desired. However, the subject adhesives of this invention are particularly suited for use in securing stainless steel hypodermic needles to glass syringe barrels. When the adhesives are used for this purpose, the resulting composite product can be readily sterilized without detrimentally affecting the bond between the needles and the syringe barrel.

The following examples will illustrate the subject invention. These examples are given for the purpose of illustration and not for purposes of limiting this invention. All parts and percents of compositions are given by weight unless otherwise specified.

EXAMPLE 1 An adhesive composition in accordance with this invention was prepared by mixing 55 parts of the epoxy composition, as represented by Formula I, with 15 parts of the epoxy composition, as represented by Formula II, and 30 parts of the epoxy composition, as represented by Formula III. These components were mixed together and then gradually heated to 200 F. This temperature was maintained for two hours. During and while maintaining this heating sequence. the components were stirred regularly until a homogeneous blend was achieved. The resulting viscose liquid composition was then removed from the oven. While in the heated condition, 9 parts of silica, 8 parts of dicyanimide and 1 part of a silane, as represented by Formula V, were blended thereinto.

The resulting composition was then milled through a three-roll mill five times in order to thoroughly blend the components. The resulting composition was then cooled to room temperature.

For purposes of securing a stainless steel needle into each of a plurality of syringes, the above-described epoxy composition was placed on the needle stem inch from the end of each needle. Care was taken to make sure that the adhesive composition completely encompassed the outer periphery of the needle. Each needle was then placed in a syringe barrel, care being taken to make sure that the adhesive composition thoroughly wet the inner periphery of the syringe barrel orifice. The resulting epoxy base adhesive material was then cured by heating the syringe barrel-stainless steel needle composite to a temperature of 450 F. for three minutes and 15 seconds. At the end of this period of time, the epoxy composition was thoroughly cured and the stainless steel needle was secured in the syringe barrel. The resulting syringes were then allowed to cool to room temperature overnight.

These syringes were then tested by autoclaving and sterilizing for one hour at a pressure of 15 p.s.i. Subsequent to autoclaving and sterilizing, the syringes were removed and allowed to dry for 48 hours. The tensile strength of the adhesive bond between the stainless steel needle and the syringe barrel was then tested by pulling the needles from the syringe barrel in a Twing-Albert Tensile Testing Machine as manufactured by Twing-Albert Instrument Co. Philadelphia, Pennsylvania. The average tensile value between the resulting stainless steel needles and the syringe barrels subsequent to autoclaving was 36.5 lbs.

EXAMPLE 2 In accordance with the description given in Example 1, an adhesive composition was prepared by mixing 65 parts of the epoxy compositions, as represented by Formula I, with 15 parts of the epoxy composition, as rep resentedby Formula II, and 20 parts of the epoxy composition, as represented by Formula III. This mixture was then heated and mixed as described in Example 1. To this mixture was then added 7 parts of silica, 8.7 of dicyanimide and 1 part of a silane, as represented by Formula V. Stainless steel needles having the resultant adhesive composition applied thereto in accordance with the manner of application in Example 1 were then assembled into syringe barrels, cured and tested in accordance with the description of Example 1. The average needle to syringe barrel tensile value of the resulting syringes was 31.6 lbs.

EXAMPLE 3 represented by Formula V. Needles having the resultant adhesive composition applied thereto in the manner of Example 1 were then secured into syringe barrels and cured in accordance with the curing procedure of Example 1. The average tensile value between the resulting stainless steel needles and the syringe barrels subsequent to autoclaving was 36.5 lbs.

6 EXAMPLE 4 By way of comparison, the adhesive compositions of this invention, as described in Examples 1-3, were compared with a prior art adhesive composition. The prior art adhesive composition, as used in accordance with this example, was formed by mixing parts of an epoxy resin, as represented by Formula I, with 7 parts of silica. These compositions were then milled three times through a three-roll mill. A catalyst composition was prepared by mixing 100 parts of a polyamide hardener, which is the condensation product of a linoleic acid dimer and ethylene diamine as sold under the trademark Versamid by the General Mills Corp. of Kankakee, Il1., with four parts of a silane, as represented by Formula VI.

and 1 /2 part silica. These components were likewise milled three times through a three-roll mill.

' Equal parts of the above-described epoxy compositions and catalytic compositions were then mixed to form an adhesive composition. Stainless steel needles were then assembled into syringe barrels using this adhesive composition. The resulting needles were then cured and tested in accordance with the description given in Example 1, except that curing was efiected at 350 F. The average needle to syringe barrel tensile value of the resultant syringes was 21.6 lbs.

What is claimed is:

1. An adhesive composition which contains from about 45 to about 70 percent by weight of a first epoxy resin of the bisphenol-A/epichlorohydrin type, having an 12 value of about 0.5, from about 5 to about 15 percent by weight of a second epoxy resin of the bisphenol-A/epichlorohydrin type having an n value greater than that of said first epoxy resin, from about 5 to about 30 percent by weight of an epoxy resin of the polyglycol diepoxide type, from about 6 to about 8 percent by weight of dicyandiamide, from about 2 to about 8 percent by weight of silica, and from about 0.6 to about 5 percent by weight of glycidoxypropyltrimethoxysilane.

2. The adhesive composition of claim 1 wherein said second epoxy resin of the bisphenol-A/epichlorohydrin type utilized has the formula 0 (EH; a. o l

wherein n has a value of from 3 to 5.6.

4. The adhesive composition of claim 1 wherein the bisphenol-A/epichlorohydrin resin utilized has the formula OH; 0H CH l I A I CH2-CHCHZO C O-CHz- HCHr-O CCH3 I 0 +111 CH 0 wherein n has a value of from about .5 to about 1.5 and O O the polyglycol diepoxlde resin has a formula as specified fi CH2 CH2 O CH2 Cfi \CIh in Formula III:

Cfi; CH-CHzO[CH CH-O] CH CH OGH -Cfi CH whereinn hasavalue of frorn3 to 5.6. wherein n has a value of from about 3 to about 5.6;

5. The adhesive composition of claim 4 wherein said (d) from about 0.6 to about 5 percent of glycidoxyadhesive composition is curable at temperatures of from propyltrimethoxysilane; about 350 to about 500 F. (e) from about 6 to about 8 percent of dicyandiamide;

6. An adhesive composition for glass to metal sealing (f) from about 2 to about 8 percent of silica, all

comprising percentage on the weight basis.

(a) from about to about percent by weight of 7. The adhesive composition of claim 6 which contains;

an epoxy resin of the bisphenol-A/epichlorohydrin (a) 47.5 percent of the epoxy resin of the bisphenoltype as represented by Formula I: 35 A/epichlorohydrin type as represented by For- 0 OH OH CH I 3 l l a (b) from about 5 to about 15 percent of an epoxy (b) 12.9 percent of the epoxy resin of the bisphenolresin of the bisphenol-A/epichl0rohydrin type as A/epichlorohydrin type as represented by Formula represented by Formula II: II;

0 CH3 0H CH3 0142- 011-oH2- 0--+-C 0-cm-oHoH2 -o--+ om L 0H; J

l 5 CH2 wherein n is about 1.5; (c) 25.7 percent of the epoxy resin of the polyglycol (c) from about 5 to about 30 percent of an epoxy diepoxide type as represented by Formula III;

resin of the polyglycol diepoxide type as repre- (d) 3.5 percent of glycidoxypropyltrimethoxysilane;

sented by Formula III: (e) 6.9 percent dicyandiamide;

(f) 3.5 percent silica, all percentage on the weight References Cited basis- UNITED STATES PATENTS taifiyThe adhesive composition of clarm 6 WhICh con- 2,946,701 6/1960 Plueddemann "h- 117 124 X 3131161 8/1964 Nitzsche 260-37 SI (a) 63.6 percent of the epoxy resln of the bisphenol- 5 A/epichlorohydrin type as represented by For- 3391113 2/1968 Lopez et 260 37 mula I;

(b) 12.7 percent of the epoxy resin of the bisphenol- OTHER REFERENCES A/epichlorohydrin type as represented by Formula Lee et f q P P Y Reslns, y 1967 10 pp. 22-18. copy in Sc1ent1fic L1brary.

(c) 8.5 percent of the epoxy resin of the polyglycol diepoxide type as represented by Formula III; MORRIS: LIEBMAN Primary Examiner (d) 7.6 percent of glycidoxypropyltrimethoxysilane; MORRIS, Assistant EXamiIler (e) .8 percent dicyandiamide; (f) 6.8 percent silica, all percentage on the Weight 15 basis. 117124, 126, 132; 260-830TW UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,635,875

DATED January 18, 1972 |NVENTOR(S) Thomas D. Reither and Ralph E. Trease If is certified that error appears inthe above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 52, centered above Formula II, insert Formula II Col. 3, line 4, centered above Formula III, insert -Formula III- Col. 5, lines 32 and 33, "representedby" should be -represented by; Col. 6, line 15, centered above Formula VI, insert -Formula VI--; line 17, "part" should be parts; Col. 6, between lines 43 and 61, that portion of the formula reading "OH CH OH CH should read -cH -c-cH :]-o-'-c-cr1 -CH2'CHCH2]O- -c-cH Col. 8, between lines 1 and 27, the formula reading CH -CH CH-OOH CHOJ CI-I CH OCH 4CH should read cri -cn/cfl ogcrl -cH-oJ cH -cr1 -o-cH2-cH-cr1 Col. 9, line 13', "7.6" should be --.8; line 14, ".8" should Signed and Scaled this Twenty-sixth Day of April 1917 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN 8 ff ce (nmmissiuner ofParem: and Trademarks 

